U.S. Pat. No. 3,824,002 issued to Terry D. Beard, entitled "Alternating Current Liquid Crystal Light Valve" and assigned to the present assignee discloses the basic principles of operation of an alternating current liquid crystal light valve which requires that a photoconductor be impedance-matched to the liquid crystal, the photocapacitance of the photoconductor being modulated in response to an input light.
U.S. Pat. No. 3,976,361 issued to Fraas, et al entitled "Charge Storage Diode With Graded Defect Density Photocapacitive Layer" and assigned to the present assignee discloses a different photocondutor for a similar light valve.
The photoconductor consists of a charge storage semiconductor diode with a graded band gap layer increasing the optical absorption coefficient of the region near the rectifying junction to permit the storage of charge.
U.S. Pat. No. 4,032,954 issued on June 28, 1977, by Jan Grinberg, et al, entitled "Silicon Single Crystal Charge Storage Diode" and assigned to the present assignee describes a species of the generic invention of U.S. Pat. No. 3,976,361. This invention presently stands allowed and will issue in due course. It discloses a charge storage photodiode silicon substrate which is doped with a slow recombination center element such as silver, to combine the advantages of a highly developed silicon manufacturing technology with the high liquid crystal stability under ac operating conditions. It is submitted that the inventions disclosed and claimed in the aforementioned patents and patent applications represent thereby significant advances in this art as explained in detail in said patents and patent application.
The aforementioned copending U.S. patent application Ser. No. 005,418 discloses the use of a charge depletion region to transfer a plurality of signals from one side of a semiconductor substrate to the opposite with good spatial resolution. As it was indicated in that application, minority carriers representing signals can be generated or injected into the transfer medium through a variety of different means. One such means that was disclosed in that application was the photogeneration of charge carriers inside the transfer medium. The present invention deals primarily with the storage and transfer of minority charge carriers created by different means.